The birth chart in the Horoscope/ Kundli is a table of planetary situation at the time of the birth of Native. Astrologer prefer this table for future prediction called vimsottari Dasha.Mahadasha has Antar dasha (sub period) and this antar dasha again comprises Pratyantar dasha (sub sub period) of planet.Whenever Mahadasha (Period of Planet) of any planet start, some get married at the beginning of the Mahadasha ( due to transit changes , get benefited by benefic/marak planets), some get the job or get promotion in the job or any abroad placement. child birth in family may happens due to these transit changes. Or some time we experience unfavourable time due to the maha dasha of malefic planet.